This invention is generally directed to the use of hydrogenated and halogenated amorphous boron compositions as electrostatographic imaging members. More specifically, the present invention is directed to photoresponsive imaging members, including layered members comprised of hydrogenated amorphous boron, that possesses photoconductive properties. In one embodiment of the present invention there are provided photoconductive imaging members comprised of amorphous boron with a band gap of from about 1.0 to about 3 electron volts, and a hydrogen content of from about 5 atomic percent to about 30 atomic percent. Also encompassed within the present invention are layered photoconductive imaging members comprised of hydrogenated amorphous boron with photoconductive properties situated on a supporting substrate, and wherein the member further includes an overcoating layer. Moreover, there is provided in accordance with the present invention imaging members comprised of hydrogenated amorphous boron, and photoconductive hydrogenated amorphous silicon. Also, in another embodiment of the present invention, the photoconductive amorphous boron is present in the imaging member in a gradient as detailed hereinafter. The aforementioned imaging members are particularly useful in electrostatographic imaging processes; and further, in some configurations the imaging members of the present invention can be selected for xerographic printing systems.
Electrostatographic imaging systems, and particularly xerographic imaging processes are extensively described in the prior art. Generally, in these processes a photoconductive material is selected for forming the latent electrostatic image thereon. The photoreceptor can be comprised of a conductive substrate containing on its surface a layer of photoconductive material, and in many instances a thin barrier layer is situated therebetween to prevent charge injection from the substrate, which could adversely effect the quality of the resulting image. Examples of known useful photoconductive materials include amorphous selenium, alloys of selenium such as selenium tellurium, selenium arsenic, and the like. Additionally, there can be selected as the imaging member various organic photoconductive materials including, for example, complexes of trinitrofluorenone and polyvinylcarbazole. Recently, there has been disclosed layered organic photoresponsive devices with arylamine hole transport molecules and photogenerating layers, reference for example U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference.
Also known are amorphous silicon photoconductors, reference for example U.S. Pat. No. 4,265,991 and 4,225,222. There is disclosed in the '991 patent an electrophotographic photosensitive member comprised of a substrate, and a photoconductive overlayer of amorphous silicon containing 10 to 40 atomic percent of hydrogen, and having a thickness of 5 to 80 microns. Additionally, this patent describes several processes for preparing amorphous silicon. In one process embodiment, there is prepared an electrophotographic photosensitive member which involves heating the member present in a chamber to a temperature of 50.degree. C. to 350.degree. C., introducing into the chamber a gas with silicon and hydrogen atoms, providing an electrical discharge in the chamber by electric energy to ionize the gas, wherein there is deposited amorphous silicon on the substrate at a rate of 0.5 to 100 Angstroms per second by utilizing an electric discharge thereby resulting in an amorphous silicon photoconductive layer of a predetermined thickness. Although the amorphous silicon device described in this patent is photosensitive, after a minimum number of imaging cycles, less than about 1,000 for example, unacceptable low quality images of poor resolution with many deletions may result. With further cycling, that is subsequent to 1,000 imaging cycles and after 10,000 imaging cycles, the image quality may continue to deteriorate often until images are partially deleted.
There are also illustrated in copending applications photoconductive imaging members comprised of amorphous silicon. Accordingly, for example, there is disclosed in copending application U.S. Ser. No. 695,990, entitled Electrophotographic Devices Containing Compensated Amorphous Silicon Compositions, the disclosure of which is totally incorporated herein by reference, an imaging member comprised of a supporting substrate and an amorphous hydrogenated silicon composition containing from about 25 parts per million by weight to about 1 percent by weight of boron compensated with substantially equal amounts of phosphorous. Furthermore, described in copending application U.S. Pat. No. 4,544,617, entitled Electrophotographic Devices Containing Overcoated Amorphous Silicon Compositions, the disclosure of which is totally incorporated herein by reference, are imaging members comprised of a supporting substrate, an amorphous silicon layer, a trapping layer comprised of doped amorphous silicon, and a top overcoating layer. Additionally, described in copending application U.S. Pat. No. 4,613,556, entitled Heterogeneous Electrophotographic Imaging Members of Amorphous Silicon, the disclosure of which is totally incorporated herein by reference, are imaging members comprised of hydrogenated amorphous silicon photogenerating compositions, and a charge transporting layer of plasma deposited silicon oxide. There is further disclosed in the latter copending application an interface transition gradient between the silicon oxide charge transport layer and the photogenerating layer.
Moreover, described in copending application U.S. Ser. No. 751,820 entitled Electrophotographic Imaging Members With Amorphous Carbon, the disclosure of which is totally incorporated herein by reference, are photoresponsive imaging members comprised of hydrogenated amorphous carbon, or halogenated amorphous carbon. More specifically, in accordance with the teachings of the aforementioned copending application there is illustrated a photoresponsive imaging member comprised of a supporting substrate, and in contact therewith hydrogenated amorphous carbon, or halogenated amorphous carbon with a band gap of from about 0.5 to about 5 electron volts.
Other representative prior art patents that disclose amorphous silicon imaging members include, for example, 4,357,179 directed to methods for preparing imaging members containing high density amorphous silicon or germanium; U.S. Pat. No. 4,237,501 which discloses a method for preparing hydrogenated amorphous silicon wherein ammonia is introduced into a reaction chamber; U.S. Pat. Nos. 4,359,514; 4,404,076; 4,403,026; 4,397,933; 4,416,962; 4,423,133; 4,461,819; 4,490,453; 4,237,151; 4,356,246; 4,361,638; 4,365,013; 3,160,521; 3,160,522; 3,496,037; 4,394,426; and 3,892,650.
Although the above-described amorphous silicon photoresponsive imaging members, including the compensated members, may be useful for their intended purposes, there continues to be a need for new imaging members. Also, there is a need for improved photoconductive materials which can be continuously used in a number of imaging cycles without deterioration therefrom. Additionally, there is a need for improved photoresponsive imaging members comprised of hydrogenated amorphous boron which are humidity insensitive and are not adversely effected by the electrical consequences resulting from scratching and abrasion. Moreover, there is a need for improved photoconductive imaging members comprised of hydrogenated amorphous boron which can be prepared with a minimum number of processing steps, and wherein the layers are sufficiently adhered to one another to enable the continuous use thereof in repetitive imaging and printing processes. Furthermore, there continues to be a need for halogenated amorphous boron photoconductive substances which can be selected for incorporation into electrostatographic imaging processes; and wherein these substances are not sensitive to humidity and corona ions generated by the charging apparatus thereby allowing the use thereof over a substantial number of imaging cycles without causing a degradation in image quality, and which members possess other desirable characteristics. In addition, there is a need for photoresponsive imaging members wherein hydrogenated amorphous boron can be selected as a transporting layer, and wherein the member further includes therein a photogenerating substance such as amorphous silicon. Additionally, there is a need for photoresponsive imaging members wherein the surface thereof is believed to be chemically more stable than hydrogenated amorphous silicon. There is also a need for a relatively nonhazordous process enabling the preparation of photoresponsive imaging members, wherein there can be selected diborone gases which are chemically more stable than silianes, or disilanes used in the generation of hydrogenated amorphous silicon imaging members.